<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .box{
            width: 200px;
            height: 200px;
            background-color: red;
            display: inline-block;
            font-size: 3em;
        }
        .two{
            background-color: blue;
            /* 相对定位到底是相对谁？
             * 相对于自己原本的位置
             * 而且它不会脱离文档流
             */
            position: relative;
            top: 20px;
            left: 20px;
        }
    </style>
</head>
<body>
    <div class="wrap">
        <div class="box one">1</div>
        <div class="box two">2</div>
        <div class="box three">3</div>
        <div class="box four">4</div>
    </div>
</body>
</html>